Although the invention has other uses, it is especially adapted to be used to diagnose problems encountered on DSL lines for operating computers or other network devices. It is common practice in today's technology to use a single conventional ground wire to transmit both higher frequency DSL signals (e.g. normally above about 4 kHz) and lower frequency Conventional Telephone Signals (CTS), sometimes referred to colloquially as Plain Old Telephone Service (POTS) (normally from about 30 Hz to less than about 4 kHz). Table I shows the conventional maximum usable length of copper lines that can accommodate DSL signals.
TABLE IData Rate (DSL)Wire GaugeDistance (Max.)1.5 or 2 Mbps24 AWG (0.5 mm)18,000 ft. (5.5 Km)1.5 or 2 Mbps26 AWG (0.4 mm)15,000 ft. (4.6 Km)It has been the experience that, as the length of the lines increases, the problems encountered with the DSL signals increase, especially near the limit of the length allowable for such DSL signals to travel. This causes a large number of calls to the customer service provider technicians, who then must rely on the ability of the customer to properly find and read the necessary diagnostic information on the DSL modem. This can lead to time delays and errors in diagnostic evaluation and correction of problems. It is noted, however, that CTS signals do not experience the same number of problems at the same length of line. Therefore, it is desirable to provide a diagnostic tool for problems associated with DSL line length that is not subject to the problems associated with the DSL frequency.